On Sun, 10 Feb 2019 20:01:47 +0100 Björn Ruytenberg <bj...@bjornweb.nl> wrote:
> Hi Alex, > > Thanks for your quick response and the patch! > > I am looking into passing through a muxless GeForce GPU to a Windows guest. > > Having been through several resources, passing through muxed and desktop > cards seems quite straightforward. Either no configuration is necessary, > or exposing the (UEFI GOP) VBIOS through the ACPI _ROM method will do > the trick. From what I gather, the latter will also work with the > proprietary NVIDIA driver on Linux. However, on Windows guests, it will > simply bail out with error 43. > > I have been doing some ACPI debugging on Windows (using windbg and QEMU, > which is excellent for this :-)), and it looks like the NVIDIA driver > does several _DSM calls instead. I'm not entirely sure what these > methods do. One method contains a number of magic strings such as > `NVIDIA Certified Optimus Ready Motherboard`, which presumably lets the > driver verify it's not running in a VM. > > Rather than trying to (partially) replicate the ACPI table from the host > in the guest, I figured it might be possible to trick the NVIDIA driver > into detecting a muxed/desktop card. For this I'll need to: > > 1. Find a VBIOS with a UEFI GOP header from a non-muxless GPU, ideally > one that is the same model (muxed/desktop) or similar (Quadro). > 2. Spoof the PCI sub vendor and sub device id, or patch the VBIOS to > have these match my own card. > 3. Spoof the PCI device class, changing it from 0302 (3D controller, > i.e. muxless card) to 0300 (VGA device). > > Now that your patch enables the last, I'll try and see if this works. If > you are interested, I'd be happy to report back the results. I'm certainly curious to see what you find, I imagine others are too. When I looked at Optimus on a Thinkpad it looked like some of the _DSM calls were hooking into SMI services, so they're beyond obfuscated. Good luck! Thanks, Alex _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://www.redhat.com/mailman/listinfo/vfio-users
